Method for manufacturing light-emitting device

ABSTRACT

A light-emitting device comprising a package comprising a light-emitting element comprising a first surface and a second surface opposite to the first surface, a first light-transmissive member arranged on the second surface of the light-emitting element, paired electrodes at the first surface of the light-emitting element, and a first covering member covering the light-emitting element such that the paired electrodes are exposed from the first covering member. The light-emitting device further comprises a light-guiding plate on which the package is placed, and a second covering member arranged on the light-guiding plate and covering laterally the package. The light-emitting device further comprises paired wirings continuously covering the paired electrodes exposed and the first covering members and being connected to the paired electrodes respectively. The paired wirings are formed by irradiation of laser light on a metal paste layer continuously covering the paired electrodes and the first covering member to remove the metal paste layer between the paired electrodes, the metal paste layer comprising a mixture of a resin and metal powder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/774,614, filed Jan. 28, 2020, which is based upon and claimsthe benefit of priorities from Japanese Patent Application No.2019-013385 filed on Jan. 29, 2019, Japanese Patent Application No.2019-039687 filed on Mar. 5, 2019, Japanese Patent Application No.2019-059486 filed on Mar. 26, 2019, and Japanese Patent Application No.2019-238083 filed on Dec. 27, 2019. The entire contents of theseapplications are incorporated herein by reference.

BACKGROUND 1. Field

Embodiments of the present invention relate to a method formanufacturing a light-emitting device.

2. Description of Related Art

A small light-emitting device is known, in which an encapsulating membercontaining a reflecting material covers the lateral and lower surfacesof a light-emitting element instead of a housing for accommodating thelight-emitting element and in which plated electrodes are arranged incontact with the lower surfaces of bump electrodes of the light-emittingelement and the lower surface of the encapsulating member (for example,Japanese Unexamined Patent Application Publication No. 2012-124443).

A method for manufacturing a light-emitting device is known thatincludes forming a metal layer continuously covering paired electrodesand a covering member and removing a portion of the metal layer byirradiation with laser light (for example, Japanese Unexamined PatentApplication Publication No. 2017-118098).

SUMMARY

An object of embodiments of the present invention is to provide alight-emitting device.

According to one aspect of the present invention, a light-emittingdevice includes a package including a light-emitting element comprisinga first surface and a second surface opposite to the first surface, afirst light-transmissive member arranged on the second surface of thelight-emitting element, paired electrodes at the first surface of thelight-emitting element, and a first covering member covering thelight-emitting element such that the paired electrodes are exposed fromthe first covering member. The light-emitting device further includes alight-guiding plate on which the package is placed, and a secondcovering member arranged on the light-guiding plate and coveringlaterally the package. The light-emitting device further includes pairedwirings continuously covering the paired electrodes exposed and thefirst covering members and being connected to the paired electrodesrespectively. The paired wirings are formed by irradiation of laserlight on a metal paste layer continuously covering the paired electrodesand the first covering member to remove the metal paste layer betweenthe paired electrodes, the metal paste layer comprising a mixture of aresin and metal powder.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed evaluation of embodiments of the invention and many ofthe accompanying advantages thereof will be given in the detaileddescription referring to the following drawings.

FIG. 1A is a schematic perspective view of a package according to anembodiment of the present invention.

FIG. 1B is a schematic bottom view of the package according to theembodiment.

FIG. 1C is a schematic cross-sectional view of the package according tothe embodiment.

FIG. 2A is a schematic cross-sectional view showing a method formanufacturing a light-emitting device according to the embodiment.

FIG. 2B is a schematic cross-sectional view showing the method formanufacturing a light-emitting device according to the embodiment.

FIG. 2C is a schematic cross-sectional view showing the method formanufacturing a light-emitting device according to the embodiment.

FIG. 2D is a schematic cross-sectional view showing the method formanufacturing a light-emitting device according to the embodiment.

FIG. 2E is a schematic cross-sectional view showing the method formanufacturing a light-emitting device according to the embodiment.

FIG. 3A is a schematic bottom view showing the method for manufacturinga light-emitting device according to the embodiment.

FIG. 3B is a schematic bottom view showing the method for manufacturinga light-emitting device according to the embodiment.

FIG. 3C is a schematic bottom view showing the method for manufacturinga light-emitting device according to the embodiment.

FIG. 3D is a schematic bottom view showing the method for manufacturinga light-emitting device according to the embodiment.

FIG. 4A is a schematic plan view of the light-emitting device accordingto the embodiment.

FIG. 4B is a schematic perspective view of the light-emitting deviceaccording to the embodiment.

FIG. 5 is a schematic perspective view of a light-emitting deviceaccording to a second embodiment viewed from a light-guiding plate.

FIG. 6 is a schematic cross-sectional view of the light-emitting deviceaccording to the second embodiment.

FIG. 7 is a schematic plan view of the light-emitting device accordingto the second embodiment.

FIG. 8 is a schematic plan view of a light-emitting device according toa third embodiment.

FIG. 9 is a schematic cross-sectional view of a light-emitting deviceaccording to a fourth embodiment.

FIG. 10A is a schematic view schematically showing a variation of apackage which can be employed in the respective embodiments.

FIG. 10B is a schematic view schematically showing a variation of apackage which can be employed in the respective embodiments.

FIG. 11 is a schematic cross-sectional view related to a fifthembodiment.

FIG. 12 is a schematic cross-sectional view related to a sixthembodiment.

FIG. 13 is a schematic cross-sectional view related to a seventhembodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described in detail on thebasis of the accompanying drawings. The descriptions below include termsindicating specific directions or positions (such as “up”, “down”,“right”, “left”, and other terms containing the meanings of these terms)as appropriate. Use of these terms is, however, intended to facilitateunderstanding of the invention referring to the drawings, and themeanings of these terms do not limit the technical scope of the presentinvention. Portions with the same reference numeral in a plurality ofdrawings represent the same portion or member. The same names are usedto describe resin members such as a first light-transmissive member, asecond light-transmissive member, and a covering member regardless ofwhether or not the members have been formed, solidified, cured, orsingulated. That is, the same name is used to describe such a member ofwhich state changes depending on stages in the process as to be in aliquid body before forming, be in a solid body after forming, and be asolid body having a different shape through division of the formed body.

FIG. 1A to FIG. 1C show a package 10 according to an embodiment. FIG. 1Ais a schematic perspective view of the package according to theembodiment from above. FIG. 1B is a schematic bottom view of the packageaccording to the embodiment. FIG. 1C is a schematic cross-sectional viewof the package according to the embodiment taken along the line IC-IC ofFIG. 1B. The package 10 will be described as an example of anintermediate structure, but various forms are possible so far as alight-emitting element 1 and a first covering member 2 are included.

The package 10 includes the light-emitting element 1, the first coveringmember 2, a first light-transmissive member 3, a secondlight-transmissive member 4, and paired electrodes 5. The shape of thepackage 10 is a rectangular body, but any shapes may be employed. In aplan view, the light-emitting element 1 may have a rectangular shape butmay have a polygonal shape such as a triangular shape, a pentagonalshape, or a hexagonal shape. For example, the light-emitting element 1includes a first semiconductor layer, an active layer, and a secondsemiconductor layer on a substrate, wherein a portion of the activelayer and a portion of the second semiconductor layer are removed. Thelight-emitting element 1 has a first surface and a second surfaceopposite to the first surface and includes the paired electrodes 5 atthe first surface. The statement that “the light-emitting element 1includes the paired electrodes 5 at the first surface” indicates thatnot only the case in which the electrodes are directly formed on thelight-emitting element 1 but also the case in which the electrodes areindirectly formed with another member such as a semiconductor layer ormetal disposed therebetween is included. The paired electrodes 5 includea first electrode 5 a and a second electrode 5 b with differentpolarities. The first electrode 5 a is electrically connected to thefirst semiconductor layer, and the second electrode 5 b is electricallyconnected to the second semiconductor layer. The firstlight-transmissive member 3 is arranged on the second surface of thelight-emitting element 1. The size of the first light-transmissivemember 3 may be larger than, equal to, or smaller than the secondsurface of the light-emitting element 1 in a plan view. In the case inwhich the size of the first light-transmissive member 3 is equal to orlarger than the size of the second surface of the light-emitting element1, the second light-transmissive member 4 may be arranged in the lateralsides of the light-emitting element 1. The first light-transmissivemember 3 has a rectangular shape in a plan view, but a polygonal shapesuch as a triangular shape, a pentagonal shape, or a hexagonal shape,may be employed. The second light-transmissive member 4 preferably bondsthe light-emitting element 1 to the first light-transmissive member 3.The first covering member 2 is arranged to cover the first surface andthe lateral surfaces of the light-emitting element 1, the firstlight-transmissive member 3, and the second light-transmissive member 4such that the surfaces of the paired electrodes 5 are exposed. The firstcovering member 2 may be formed in one step or in two or more steps. Incase that the first covering member 2 is formed in two or more steps, itmay be formed with a plurality of layers, or it may be also formed withone layer, without an interface.

A light-emitting device may be produced in the steps below, using thepackage described above. FIG. 2A to FIG. 2E are schematiccross-sectional views showing a method for manufacturing alight-emitting device according to the embodiment. Two packages are usedin this example, which does not limit the present invention. A pluralityof packages may be used. FIG. 3A to FIG. 3D are schematic bottom viewsshowing the method for manufacturing a light-emitting device accordingto the embodiment. FIG. 4A is a schematic plan view of thelight-emitting device according to the embodiment. FIG. 4B is aschematic perspective view of the light-emitting device according to theembodiment. FIG. 4A shows the state before singulation of thelight-emitting device, and FIG. 4B shows the singulated light-emittingdevice.

The method for manufacturing a light-emitting device according to anembodiment includes a step of preparing an intermediate productincluding at least one light-emitting element provided with pairedelectrodes at a first surface and a first covering member covering thelight-emitting element such that respective portions of surfaces of thepaired electrodes are exposed, a step of forming a metal paste layercontinuously covering the exposed portion of the paired electrodes andthe first covering member, and a step of forming paired wirings byirradiating the metal paste layer on the paired electrodes and the metalpaste layer on the first covering member with laser light to remove themetal paste layer between the paired electrodes and a portion of themetal paste layer on the first covering member in order to prevent thepaired electrodes from being short-circuited.

A portion of the metal paste layer of the intermediate product isremoved by laser ablation using a laser light irradiated to the metalpaste layer. Patterning of the metal paste layer is thus conducted, andthe metal paste layer can be formed into the wirings or externalconnection electrodes. The laser ablation is a phenomenon that thesurface of a solid is removed when the radiation intensity of laserlight applied to the surface of the solid reaches or exceeds a certainmagnitude (threshold). Patterning of the metal paste layer can beconducted by laser ablation without using a mask or the like.

For example, in case that sputtering or vapor deposition is used forforming wirings from a metal layer, its working process is complicatedand it requires sophisticated equipments, and therefore the process iscostly. In addition, the metal layer is required to be thick because athin metal layer is likely to break. However, in case that the metallayer is irradiated with laser causing ablation for forming electrodeshaving contacts of different materials and preventing a short circuitthereof, improvement in the working efficiency is necessary, because athick metal layer requires a high laser power and efforts for meltingand removing the metal layer.

On the other hand, in some embodiments, use of the metal paste layerenables easy and precise formation of the wirings. The metal paste layercontains a metal powder and a resin. Hence, the resin is likely to beflown off when the metal paste layer is irradiated with laser light, andtherefore the laser power can be greatly reduced. The laser irradiationtime can also be greatly reduced, so that the working efficiency can begreatly improved. In addition, the great improvement in the workingefficiency by laser ablation allows the metal paste layer to be thickand reduces the possibility of breakage of the wiring. Furthermore, anarrow groove line can be formed by removing a portion of the metalpaste layer by laser ablation, so that a smaller and reliablelight-emitting device can be provided.

A plurality of packages are arranged on a light-guiding plate, and anynumber of packages can be employed. For example, a large number ofpackages may be arranged on the light-guiding plate, which is singulatedinto segments each containing a total of 16 packages arranged in a 4rows×4 lines. Respective segments can be electrically connected,enabling an extendable large display, and replacement of a segment canbe easily conducted segment-wise when a segment is partially gone out.

The respective steps are explained in detail below.

Preparing an Intermediate Product

An intermediate product is prepared, including light-emitting elements 1each provided with paired electrodes 5 at a first surface and a firstcovering member 2 covering the light-emitting element 1 such thatrespective portions of surfaces of the paired electrodes 5 are exposed.

The packages 10 are placed on a light-guiding plate 30. The packages 10are preferably arranged on the light-guiding plate 30 with adhesivethird light-transmissive members 40 disposed therebetween. The firstlight-transmissive members 3 of the packages 10 are preferably incontact with the light-guiding plate 30. The third light-transmissivemembers 40 preferably cover the lateral surfaces of the firstlight-transmissive members 3 and the lateral surfaces of the firstcovering members 2. This allows light emitted from the light-emittingelements 1 to spread out in the lateral direction. It is preferable thata plurality of packages 10 be systematically arranged on thelight-guiding plate 30 in the longitudinal and lateral directions. It ispreferable that the packages 10 arranged on the light-guiding plate 30are laterally covered with a second covering member 50. The thickness ofthe second covering member 50 is preferably smaller than the thicknessof the package 10, but the thickness of the second covering member 50may be equal to or larger than the thickness of the package 10. This isfor ease of formation of a metal paste layer 25 or the wirings 20. Thepaired electrodes 5 preferably contain Cu because Cu has good electricalconductivity.

A flat plate may be used as the light-guiding plate 30, and recesses inwhich the packages 10 are to be arranged may be formed in a portion ofthe flat plate. The shape of each of the recesses is preferablyrectangular in a plan view and similar to the shape of the package 10,but a polygonal shape such as a triangular shape, a pentagonal shape, ora hexagonal shape, may be employed. The depth of the recess may be equalto or smaller than the height of the package 10. If the depth of therecess is smaller than the height of the package 10, a portion of thepackage 10 is projected from the light-guiding plate 30 in across-sectional view. In this case, the lateral surfaces of the package10 may be covered with the second covering member 50.

The distance between adjacent light-emitting elements 1 can be selectedas appropriate depending on the intended size of the light-emittingdevice 100 and the size of the light-emitting elements 1. Thelight-emitting elements 1 are arranged taking the cut margin (width of acutting blade) into account, because singulation is performed later bycutting the covering member.

The first covering member 2 is arranged between the paired electrodes 5on the first surface of each light-emitting element 1. The distancebetween the paired electrodes 5 is preferably 10 μm or more,particularly preferably 20 μm or more. The distance between the pairedelectrodes 5 is preferably 100 μm or less, particularly preferably 50 μmor less. This structure facilitates formation of the paired wirings byirradiation with laser light described later, so that small packages 10can be used. The distance between the electrodes 5 is preferably setaccording to a spot size of the laser light, and, preferably, thedistance is small to an extent such that a short circuit is not caused.

Forming Metal Paste Layer

A metal paste layer is formed to continuously cover the pairs ofelectrodes 5 exposed and the first covering members 2.

A plurality of packages 10 are respectively arranged on thelight-guiding plate 30 with a third light-transmissive member 40disposed therebetween, and the second covering member 50 is arrangedlaterally to the package 10. The metal paste layer 25 is continuouslyarranged over the first covering members 2 and the second coveringmember 50. The metal paste layer 25 is preferably formed by eitherprinting or spray coating. Printing can be performed by either gravureprinting, relief printing, planographic printing, or screen printing,preferably screen printing. Spray coating can be performed by any ofinkjet, air spray coating, or jet spary coating. The metal paste layer25 and therefore the wirings 20 can be easily formed without requiringsophisticated equipment for sputtering or vapor deposition. Thethickness of the metal paste layer 25 is preferably 1 μm or more, morepreferably 3 μm to 50 μm, and particularly preferably 5 μm to 20 μm.Through arranging the metal paste layer 25 to have a predeterminedthickness or more, the electrical continuity can be ensured, so that thereliability can be improved. If the metal paste layer 25 has apredetermined thickness, the electric resistance can be reduced. Even incase that the metal paste layer 25 has a predetermined thickness asdescribed above, the wirings 20 can be easily formed by laser ablation.The width of the metal paste layer 25 is not particularly important sofar the electrical continuity is ensured. For example, the width ispreferably 200 μm to 1,000 μm, particularly preferably 400 μm to 700 μm.

It is preferable that, in the step of preparing an intermediate product,a plurality of light-emitting elements 1 are used, then in the step offorming a metal paste layer 25, the metal paste layer 25 is formedcontinuously covering the light-emitting elements 1, and then thelight-emitting elements 1 are electrically connected in the step offorming the wirings 20, as explained later. The light-emitting elements1 can thus be easily wired.

The metal paste layer 25 used here is preferably a mixture of a resinand metal powder, which may further contain an organic solvent. The sizeof the metal powder particle is preferably 0.01 μm to 10 μm,particularly preferably 0.1 μm to 5 μm. The electrical conductivity canbe varied by controlling the particle size of the metal powder used inthe metal paste layer 25. When the metal paste layer 25 is printed, itsviscosity may be adjusted. The resin may be in powder or in liquidbefore the metal paste layer 25 is cured.

The metal powder preferably includes at least one of silver powder,copper powder, and silver or copper powder coated with a metal. Theelectrical conductivity can therefore be enhanced.

The concentration of the metal powder in the metal paste layer 25 ispreferably between 60 wt % and 95 wt %. By increasing the concentrationof the metal powder, the electrical conductivity can be enhanced, andthe electric resistance can be kept low. By setting the proportion in apredetermined range, printing or the like can be easily performed.

Forming Paired Wirings

The metal paste layer 25 continuously covering the paired electrodes 5and the first covering member 2 is irradiated with laser light to removethe metal paste layer 25 between the paired electrodes 5 and a portionof the metal paste layer 25 on the first covering member 2 to formpaired wirings 20, first wiring 20 a, second wiring 20 b, so thatshort-circuiting of the paired electrodes 5 is prevented. The firstwiring 20 a and the second wiring 20 b are formed from the metal pastelayer 25 by cutting a portion of the metal paste layer 25, and not madeof a material different from the material of the metal paste layer.Further, removing the portion of the metal paste layer 25 by irradiationwith laser light, the metal paste layer 25 is cut between the pairedelectrodes 5 of a light-emitting element 1, which results in pairedwirings 20, the first wiring 20 a and the second wiring 20 b, thoughthey are still continuous with the metal paste layer 25 covering theelectrodes of another adjacent light-emitting element 1. In other words,if the metal paste layer 25 is cut between the electrodes 5 of onelight-emitting element 1 and remains continuous between the electrodes 5of one light-emitting element 1 and the electrode 5 of anotherlight-emitting element 1, the metal paste layer 25 does not function asthe wiring 20 for simultaneous driving of two light-emitting elements.

For example, the first wiring 20 a and the second wiring 20 b may alsobe formed so that one wiring 20 drives two light-emitting elementssimultaneously (FIGS. 3A-3D). The metal paste layer 25 is formed byprinting or spray-coating, and by curing the resin contained in themetal paste layer 25. Heating or laser irradiation can be employed forcuring. The cured metal paste layer 25 is irradiated with laser light.Pulsed irradiation of laser light is preferable, and the spot size oflaser light is appropriately adjusted. The number of pulses ispreferably one to ten, particularly preferably two to five. By employinga larger thickness of the metal paste layer 25, the electricalconductivity can be increased and the electric resistance can bereduced, though the number of pulses should be increased in order to cutthe metal paste layer 25 for preventing the first electrode 5 a and thesecond electrode 5 b from short-circuiting. Increasing the number ofpulses increases the time of forming the paired wirings 20, and it istherefore preferable to keep small the number of pulses. Hence, thenumber of pulses is preferably two to five. Though pulses may be appliedsuccessively at the same position, however, because this causes heataccumulation at the position, the laser may be preferably moved toprevent successive application of pulses at a same position, and theposition may be re-irradiated with a pulse after a predetermined periodof time. Use of a laser enables micromachining and keeping a highaccuracy of cutting position. The intensity of the laser light, thediameter of the irradiation spot, and the moving speed between theirradiation spots can be selected in consideration of thermalconductivities of the first covering member 2 and the metal paste layer25 and the difference in these thermal conductivities so that laserablation occurs on the metal paste layer 25 above the first coveringmember 2.

The emission wavelength of the laser may be in the infrared range (forexample around 1064 nm), red range (for example, around 640 nm), greenrange (for example, around 532 nm), or in a range shorter than green,such as blue or ultraviolet range (for example, around 355 nm). Byemploying a wavelength in the ultraviolet range, the generationefficiency of ablation can be improved and the high degree of massproduction can be realized. Further, the pulse width of the laser can bein the orders of nanosecond, picosecond, or femtosecond. For example, alaser having a wavelength of around 532 nm in the green range and apulse width of nanosecond order is preferably used in view of power andworking efficiency.

Irradiation with laser light having a width smaller than the distancebetween the paired electrodes 5 is preferable. For example, when thedistance between the first electrode 5 a and the second electrode 5 b is30 μm, the distance of 30 μm between the first wiring 20 a and thesecond wiring 20 b can be realized using a laser with a processing widtharound 30 μm. Though, the laser light is preferably applied in avertical direction at an angle of 90° with respect to surface of themetal paste layer 25 from a viewpoint of effectivity of laser energyconcentration, the laser light is applied from diagonally above at anangle between 45° and 145°, preferably at an angle between 70° and 110°with respect to the surface of metal paste layer 25.

As the resin and the metal powder of the metal paste layer 25 are flownoff by laser irradiation, these dusts are collected. The dust collectionis preferably performed in a direction parallel to the surface of thelight-guiding plate 30 or at an angle of 30° or less with respect to thesurface of the light-guiding plate 30.

In forming paired wirings 20, as the first covering member 2 is disposedon the first surface of the light-emitting element 1 and between thepaired electrodes 5, it is preferable that the first covering member 2between the paired electrodes 5 is partially removed by laser light. Inother words, the first covering member 2 disposed between the pairedelectrodes 5 is not completely removed by laser light but is partiallyleft. As the first covering member 2 is insulating, the remaining firstcovering member 2 prevents the first wiring 20 a and the second wiring20 b from being short-circuited. Preferably, the thickness of theremaining first covering member 2 is ⅕ to ⅘ of the thickness of theelectrodes 5.

The method of laser irradiation is described. A plurality oflight-emitting elements 1 are arranged in the row and column directionson the light-guiding plate 30. On the light-emitting elements 1, themetal paste layer 25 with a predetermined width is disposed. Laser lightis applied between the pairs of electrodes 5 of a light-emitting element1. As the light-emitting element 1 is arranged at predeterminedpositions, laser irradiation between the pairs of electrodes 5 can beperformed even though the pairs of electrodes 5 of the light-emittingelements 1 cannot be visually recognized directly. In this case, it ispreferable that the distance between the paired electrodes 5 is about1.5 times to 5 times larger than the spot size of the laser light inconsideration of positional deviations of laser irradiation.

In another method, it is preferable that the paired electrodes 5 of alight-emitting element 1 are first recognized in the step of preparingan intermediate product, and, in the step of forming paired wirings,laser light is applied between the paired electrodes 5 of thelight-emitting element 1 recognized in the step of preparing theintermediate product. If the positions of the paired electrodes 5 of thelight-emitting element 1 are recognized in advance as explained above,because the laser light can be applied to appropriate positions takingthe positional shifts of the light-emitting element 1 in up/downdirection and rotation of the light-emitting element 1 into account, asmall light-emitting element 1 in which the distance between the pairedelectrodes 5 is small can be employed.

After forming the paired wirings, a step of covering at least the pairedelectrodes 5 with an insulating member 60 may be further included. Thepaired electrodes 5 may be occasionally exposed by laser ablation insome cases, but the short circuit can be prevented by covering thepaired electrodes 5 with the insulating member 60. The insulating member60 may cover not only the paired electrodes 5 but also the pairedwirings 20 and the second covering member 50. In the step of coveringpaired electrodes 5 with the insulating member 60, the insulating member60 is preferably colored. Though the insulating member 60 may betransparent, translucent, or opaque, it is preferable that theinsulating member 60 is visually transparent or translucent, ortransparent or translucent in the wavelength range used in a measuringinstrument, for checking the state of connection between the wirings 20.The measuring instrument is preferably a spectrophotometer utilizinglight such as blue light with a peak wavelength of 480 nm, green lightwith a peak wavelength of 520 nm, or red light with a peak wavelength of600 nm, but it is not limited to these wavelengths. Though theinsulating member 60 is preferably colorless and transparent, inparticular, it is preferable to be colored in a certain extent allowingfor confirmation that the insulating member 60 is arranged on the firstcovering member 2 and the like and for checking the state of connectionbetween the wirings portions 20 through the insulating member 60. Forexample, the insulating member 60 preferably contains a coloring agent,a colorant, a pigment, or a dye of a color such as blue, green, or red.For example, the light transmission of the insulating member 60 may be20% to 95%, preferably 30% to 80%. The light transmission of theinsulating member 60 is measured with a transmission measuringinstrument. The insulating member 60 is preferably a film-like, and thethickness of the insulating member 60 is preferably 0.5 μm to 100 μm.For example, the insulating member 60 preferably has a circular,elliptic, or rectangular shape having a size with a maximum diameter 0.5to 3 times as large as the maximum diameter of the package 10.

Package

The package 10 includes at least a light-emitting element 1 and a firstcovering member 2 and may further include a first light-transmissivemember 3 and a second light-transmissive member 4. The light-emittingelement 1 includes paired electrodes 5 on the first surface. The firstcovering member 2 is only required to be insulating because the firstcovering member 2 covers the lateral surfaces of the light-emittingelement 1. The first covering member 2 is preferably reflective but mayalso be light transmissive. The reflective first covering member 2 maybe, for example, a member containing about 60 wt % of silica and whitetitanium oxide in a silicone resin and can be formed by compressionmolding, transfer molding, injection molding, printing, or spraycoating. The first covering member can be formed plate-like and be cutinto a rectangular body having a predetermined size.

A liquid second light-transmissive member 4 is applied on theplate-shaped first light-transmissive member 3 to bond each of thelight-emitting elements 1. The liquid second light-transmissive members4 are formed, being separated from one another. Each of the secondlight-transmissive members 4 can have any shape corresponding to theshape of the light-emitting element 1 in a plan view, for example,square, rectangle, circle, and ellipse. It should be noted that thedistances between adjacent second light-transmissive members 4 can beappropriately selected according to the outer shape and to the number ofpackages 10 arranged at once. Further, each second light-transmissivemember 4 is preferably formed to cover about 70% to 150% of the areacovered by the package 10 in the plate-shaped first light-transmissivemember 3.

When the light-emitting element 1 is arranged on the firstlight-transmissive member 3 applied with the liquid second transmissivemember 4, the second light-transmissive member 4 creeps up the lateralsurfaces of the light-emitting element 1. Accordingly, in the state inwhich the light-emitting element 1 is placed on the firstlight-transmissive member 3, the outer surfaces of the secondlight-transmissive member 4 is formed extending obliquely upward. Forexample, the second light-transmissive member 4 and the light-emittingelement together forme a truncated square pyramid. The light-emittingelement 1 may be pressed as necessary after being arranged on the firstlight-transmissive member 3. After arranging the light-emitting element1, the liquid second light-transmissive member 4 is heated to form acured second light-transmissive member 4.

It should be noted that, though the above light-emitting element 1 andfirst light-transmissive member 3 are bonded via the secondlight-transmissive member 4 existing between them, they may be directlybonded without the second light-transmissive member. Namely, afterarranging the light-emitting element 1 on the first light-transmissivemember 3, the liquid light-transmissive member 4 is applied around thelight-emitting element 1.

Next, the package 10 is placed on the light-guiding plate 30 via aliquid third light-transmissive member 40 disposed therebetween so thatthe first light-transmissive member 3 to be in contact with thelight-guiding plate 30. Similarly to the case of the above secondlight-transmissive member 4, a liquid third light-transmissive member 40forms an outer surface extending obliquely upward to the package 10, andthe third light-transmissive member is cured. The second covering member50 is provided to integrally covers a plurality of packages 10. Thesecond covering member 50 may be, for example, a member containing about60 wt % of silica and white titanium oxide in a silicone resin and canbe formed by compression molding, transfer molding, injection molding,printing, or spraying.

The thickness of the second covering member 50 may be reduced by a knownprocess method so that the pairs of electrodes 5 of the light-emittingelements 1 are exposed, after the entire second covering member 50 iscovered, covering the packages 10 arranged on the light-guiding plate30, and after the second covering member 50 is cured. Thus, alight-emitting device 100 having a predetermined thickness can beobtained. Further, the surface of each paired electrodes 5 of respectivepackages 10 and the surface of the second covering member 50 can beflush, and thus the metal paste layer 25 can be easily printed.

The term “plate-like” here describes a member having a large area onwhich one or more light-emitting elements can be arranged, and this termcan be replaced with other term such as sheet-like, film-like, orlayer-like.

Light-Emitting Element

As a light-emitting element 1, for example, a semiconductorlight-emitting element such as a light-emitting diode can be used, and alight-emitting element that can emit visible light such as blue, green,or red light can be used. The semiconductor light-emitting elementincludes a layered structure including a light-emitting layer andelectrodes. The layered structure has the first surface on which theelectrodes are formed and the second surface opposite to the firstsurface serving as the light-extracting surface.

The layered structure includes semiconductor layers including alight-emitting layer. Further, the layered structure may include alight-transmissive substrate such as a sapphire substrate. An example ofthe semiconductor layered body can include three semiconductor layers: afirst conductive semiconductor layer (such as an n-type semiconductorlayer), the light-emitting layer (active layer), and a second conductivesemiconductor layer (such as a p-type semiconductor layer). As asemiconductor layer (an active layer) that can emit ultraviolet light orvisible light in the blue to green region can be formed from, forexample, a semiconductor material such as group III-V compoundsemiconductor. Specifically, a nitride semiconductor material such asIn_(X)Al_(Y)Ga_(1-X-Y)N (where 0≤X, 0≤Y, and X+Y≤1) can be used.Examples of a semiconductor layered body that can emit red light includeGaAs, GaAlAs, GaP, InGaAs, and InGaAsP. The electrodes are preferablymade of copper.

First Covering Member

The first covering member 2 is preferably a resin member having a maincomponent of a thermosetting resin such as silicone resins, modifiedsilicone resins, epoxy resins, or phenol resins.

The first covering member 2 is preferably a light-reflective resinmember. The light-reflective resin refers to a resin material whosereflectance with respect to light emitted from the light-emittingelement is 70% or more. For example, a white resin is preferable. Thelight extraction efficiency of the light-emitting device is enhancedbecause light that has reached the first covering member is reflectedtoward the light emission surface of the light-emitting device. Alight-transmissive resin member may be used as the first covering member2. In this case, a material that is same as or similar to the materialused for the first light-transmissive member described later can be usedfor the first covering member.

As the light-reflective resin, for example, a light-transmissive resinincluding a light-reflective substance dispersed therein can be used. Asthe light-reflective substance, for example titanium oxide, siliconoxide, zirconium oxide, potassium titanate, aluminum oxide, aluminumnitride, boron nitride, and mullite are suitable. Though, for the lightreflective material, a particle-like, fibrous, or flaky light-reflectivesubstance can be used, a fibrous one is particularly preferable becausean effect of reducing the thermal expansion coefficient of the firstcovering member can also be expected.

For example, in case that the first covering member is constituted of aresin member containing a filler such as a light-reflective substance,the resin component at the surface irradiated with laser light isremoved by ablation and the filler is exposed at the surface. Theirradiation spot of laser light is continuously or successively moved onthe surface, so that grooves are formed in a striped pattern along thedirection of movement. The grooves formed have a width of, for example,about 10 μm to 100 μm, typically 40 μm, and a depth of 0.1 μm to 3 μm,depending on the diameter of the irradiation spot of laser light.

First Light-Transmissive Member

The first light-transmissive member 3 is arranged on the second surfaceof the light-emitting element. For the material of the firstlight-transmissive member 3 resin, glass, etc. may be used. As examplesfor the resin, a thermosetting resin such as silicone resin, modifiedsilicone resin, epoxy resin, or phenolic resin and thermoplastic resinsuch as polycarbonate resin, acrylic resin, methylpentene resin, orpolynorbornene resin can be used. A silicone resin, which has a goodlight resistance and a good heat resistance, is particularly suitable.

The first light-transmissive member 3 may contain a phosphor as awavelength conversion material in addition to the light-transmissivematerial described above. A phosphor that can be excited by lightemitted from the light-emitting element is used. Examples of a phosphorthat can be excited by a blue or ultraviolet light-emitting elementinclude yttrium-aluminum-garnet phosphors activated with cerium(YAG:Ce); lutetium-aluminum-garnet phosphors activated with cerium(LAG:Ce); nitrogen-containing calcium aluminosilicate phosphorsactivated with europium and/or chromium (CaO—Al₂O₃—SiO₂:Eu, Cr);silicate phosphors activated with europium ((Sr,Ba)₂SiO₄:Eu); nitridephosphors such as β-SiAlON phosphors, CASN phosphors, or SCASNphosphors; KSF phosphors (K₂SiF₆:Mn); sulfide phosphors; and quantum-dotphosphors. Light-emitting devices that emit various colors (such as alight-emitting device that emits white light) can be manufactured bycombining these phosphors and blue or ultraviolet light-emittingelements.

Also, the first light-transmissive member 3 may contain various fillersand the like for purposes of adjusting the viscosity, etc.

Second Light-Transmissive Member

The second light-transmissive member 4 bonds the light-emitting element1 to the first light-transmissive member 3. The secondlight-transmissive member may contain a phosphor or a filler.

The present invention is not limited to the embodiment described above.It is needless to say that any other embodiments within the scope of thepresent invention are possible.

Third Light-Transmissive Member

The third light-transmissive member 40 is a material having anadhesiveness. The third light-transmissive member 40 is preferablydisposed so that the first light-transmissive member 3 of the package 10and the light-guiding plate 30 are in contact to each other. The thirdlight-transmissive member 40 preferably covers the side surfaces of thefirst light-transmissive member 3 and the side surfaces of the firstcovering member 2. Because of such construction, the light emitted fromthe light-emitting element 1 can spread out to side directions. Thethird light-transmissive member 40 can be formed from a same material asthe second light-transmissive member 4.

Light-Guiding Plate

The light-guiding plate 30 is not limited to be simply a flat plate butmay also have recesses and projections in portions, forming sections(cells) in the plate. The packages can be arranged in recesses. Therecesses or projections may also function as lenses or the like. Forexample, depressions, a light-blocking film, or a reflective film may beformed such that the light-guiding plate 30 enables distinguishingbetween a cell with a lit-on package and a cell with a lit-off package.Further, by arranging a reflective film or a light-blocking film on thesurface of the light-guiding plate opposite to the surface on which thepackages are arranged, light emitted from the packages can spread out inthe horizontal direction through the light-guiding plate.

A light-emitting device according to a second embodiment is explainedreferring to the drawings. FIG. 5 is a schematic perspective view of thelight-emitting device according to the second embodiment viewed from thelight-guiding plate. FIG. 6 is a schematic cross-sectional view of thelight-emitting device according to the second embodiment. FIG. 7 is aschematic plan view of the light-emitting device according to the secondembodiment. Here, in the already explained step of preparing anintermediate product, the explanation about the package 10 is given,assuming that the package 10 is arranged via the thirdlight-transmissive member 40 on the light-guiding plate 31. In thesefigures, the package and the third light-transmissive member are shownfor visibility without hatching which indicates cross sections of themembers. The schematic perspective view of the light-emitting deviceaccording to the second embodiment shows one segment constituted of atotal of 16 cells in which four cells are arranged in the longitudinaldirection and four cells are arranged in the lateral direction. Aplurality of segments are combined to constitute a planar light sourceof any desired size. The schematic cross-sectional view according to thesecond embodiment (FIG. 6 ) shows a single cell of the light-emittingdevice.

A pre-arranged light-guiding plate 31 is used for the light-emittingdevice according to the second embodiment. The surface of thelight-guiding plate 31 on which the packages 10 are arranged is flat,assuming the surface opposite to the flat surface as back surface. Lightfrom the packages 10 is emitted mainly from the back surface of thelight-guiding plate 31. A single cell of the light-guiding plate 31 hasa first recess 31 a in a region in which the package 10 is arranged. Asecond recess 31 b is formed between adjacent first recesses 31 a of thelight-guiding plate 31, and the second recess 31 b is formed around anintersection point of a longitudinal line and a lateral line, forming alattice pattern. In each package 10, the light-emitting element 1 isplaced on the first light-transmissive member 3, the secondlight-transmissive member 4 is arranged on the lateral surfaces of thelight-emitting element 1, and the first covering member 2 is arrangedcovering the second light-transmissive member 4. The shape of the firstrecess 31 a is a frustum of a truncated square pyramid in a plan viewand is a trapezoid in a cross-sectional view that is wider on the upperside of the opening than on the bottom surface. The opening area of thefirst recess 31 a on the upper side of the opening is larger than thearea of the bottom surface. The package 10 is arranged such that thebottom of the frustum of the truncated square pyramid and the firstlight-transmissive member 3 are in contact. The third light-transmissivemember 40 is arranged on the lateral surfaces of the package 10. Areflective member 70 is disposed in the second recess 31 b of thelight-guiding plate 31. The flat surface of the upper surface of thereflective member 70 and the light-guiding plate 31 is covered with thesecond covering member 50. For the reflective member 70 and the secondcovering member 50, a resin mixed with light-reflective substances isused to efficiently reflect light emitted from the packages 10, so thatthe light emitted from the packages 10 is emitted from the back surfaceof the light-guiding plate 31. The second recess 31 b has inclinedsurfaces to allow light easily emit from the packages 10 to be emittedfrom the back surface of the light-guiding plate 31, and the inclinationangle is preferably such that light can be extracted in a verticaldirection from the back surface of the light-guiding plate 31. Wirings21 are arranged on the second covering member 50. A first wiring 21 a iselectrically connected to the first electrode 5 a of the package 10, anda second wiring 21 b is electrically connected to the second electrode 5b of the package 10, wherein the connecting portion of these wirings iscovered with the insulating member 60. In this case, the second recess31 b is deepest between adjacent first recesses 31 a, in other words, ata joint portion between cells. As the reflective member 70 is arrangedin the second recess 31 b, the resin used for the reflective member 70shrinks when the resin is cured, and a curved depression is likely to beformed on the upper surface of the reflective member 70 in the secondrecess 31 b. Thus, when the wirings 21 are provided by such as printing,because there is a risk that the wirings may likely to be broken,widened portions 21 c are provided to the wirings 21 for avoiding suchbreakage. The wirings 21 may be fainted or narrowed when being printed,causing an increase of electric resistance even though the wirings 21are not broken. Hence, the widened portions 21 c of the wirings 21 arepreferably arranged near the most depressed point of the second recess31 b and on the joint portions between cells. The shape of the widenedportions 21 c of the wirings 21 is not limited to be circular orelliptic but may be rectangular or polygonal, and the number thereof isnot limited to one, thus a plurality of widened portions are used, or aplurality of lines can also be used in place of these widened portions.In case that a plurality of widened portions 21 c are arranged on thejoint portions between cells, a plurality of widened portions 21 c arepreferably arranged in a substantially straight line.

Third recesses 31 c are preferably formed on the back surface of thelight-guiding plate 31 at positions opposite to the first recesses 31 a.The third recesses 31 c are preferably, for example, a conical orpolygonal pyramid. This is because conical third recesses 31 c allowlight emitted from the packages 10 to spread out in the horizontaldirections or oblique directions through the light-guiding plate 31.Light-blocking members 80 may be arranged in the third recesses 31 c.Because the light from the packages 10 is emitted most intensely to thedirection directly upward of the package, and therefore occurs likely anemission unevenness over the whole light-guiding plate 31. Thus, byarranging the light-blocking members 80 in the third recesses 31 c, thelight emitted from the packages 10 directly upward can be suppressed andthe emission unevenness can be reduced. Each of the light-blockingmembers 80 may cover the entire third recess 31 c, but preferably coversonly a portion of the third recess 31 c. For example, it is preferablethat, for example, about ¼ to ¾ of the depth of the third recess 31 c iscovered. The light-blocking member 80 preferably covers an area equal toor up to as large as the first recess 31 a, seen in a back view of thelight-guiding plate 31. The shape of the third recess 31 c afterarranging the light-blocking member 80 in the third recess 31 c ispreferably circular truncated cone in a back view.

Hence, the light-guiding plate 31 has a plurality of first recesses 31 ain which the light-emitting elements 1 are arranged and the secondrecess 31 b between adjacent first recesses 31 a. The reflective member70 is arranged in the second recess 31 b, the second covering member 50covers the reflective member 70, and the wirings 21 are arranged on thesecond covering member 50. The wirings 21 arranged on the second recess31 b preferably include the widened portions 21 c, which are portionswider than the wirings 21 arranged on the first recesses 31 a.

A light-emitting device according to a third embodiment is explainedreferring to the drawing. FIG. 8 is a schematic plan view of thelight-emitting device according to the third embodiment.

The light-emitting device according to the third embodiment issubstantially same as the second embodiment except for the wirings.Wirings 22 include widened portions 22 c between adjacent packages 10arranged in the lateral direction, particularly at the middle positionbetween adjacent packages 10. The wiring 20 is provided with a bentportion around the center of each wiring 22, being a linear-like shapehaving a step, in the lateral direction between adjacent packages 10,but the bent portion is not located at the middle position between theadjacent packages 10. By providing the wiring 22 with the bent portion,it is possible to prevent fainting or breaking of the wiring 22 whenbeing printed. Further, the wiring 22 includes a widened wiring portion22 d on the side different from the side on which the packages 10 arearranged in the lateral direction. Widening the wiring 22 can reduce theelectric resistance and prevent breakage. The length of the wiringportion 22 d in the lateral direction is not particularly limited, butthe wiring portion 22 d preferably extends to the vicinity of the wideportion 22 c in the up/down direction.

A light-emitting device according to a third embodiment is explainedreferring to FIG. 9 . FIG. 9 is a schematic plan view of thelight-emitting device according to the third embodiment. Here, it isexplained that, in the already explained step of preparing anintermediate product, the package 10 is assumed to be arranged via thethird light-transmissive member 40 on the light-guiding plate 30. Itshould be noted that the light-emitting element 1 and the secondlight-transmissive member 4 are shown for visibility without hatchingwhich indicates cross sections of the members.

The light-emitting device related to the fourth embodiment is differentfrom the other embodiments in that the package 10 is arranged in athrough-hole 30A provided in the light-guiding plate 30. It should benoted that a through-hole 30A is provided in the light-guiding plate 30corresponding the respective arranged packages. The package 10 includesa light-emitting element 1, a first light-transmissive member 3 disposedvia a second light-transmissive member 4 on the light-emitting element1, a first light-reflective film 13 arranged on the firstlight-transmissive member 3, and a first covering member 2 provided viathe second light-transmissive member 4 to the lateral sides of thelight-emitting element 1. Further, the package 10 is arranged via thethird light-transmissive member 40 on the light-guiding plate 30. Again,it is preferable that the second covering member 50 covers the lateralsides of the package 10 arranged on the light-guiding plate 30. Thoughit is preferable that the thickness of the second covering member 50 isless than the thickness of the package 10, the thickness of the secondcovering member 50 may be same or larger than the package 10. It shouldbe noted that, for arranging the package 10 in the through-hole 30Aformed in the light-guiding plate 30, a working sheet may be applied tocover the through-hole on one side.

Further, the first light-reflective film 13 arranged on the firstlight-transmissive member 3 is, as an example, formed to be flush withthe surface of the light-guiding plate 30. The first light-reflectivefilm 13 is used for reflecting or shading a light. The firstlight-reflective film 13 is preferably formed from a material whichshades or reflects at least 80% of light transmitted via the firstlight-transmissive member 3. For the first light-reflective film 13, asingle-layer film from a metal, a multi-layer film from a metal, or amulti-layer film consisting of a plurality of layers from at least twokinds of dielectric materials, namely a dielectric multi-layer film, canbe used. The first light-reflective film 13 can be formed by, forexample, by sputtering method. In a plan view, the firstlight-reflective film 13 may have a same area as the firstlight-transmissive member 3 or may have a larger area than the firstlight-transmissive material 3. This is because the light emitted upwardsfrom the light emitting element 1 can be guided to lateral side byarranging the size of the first light-transmissive member 3 larger. Whenthe area of the first light-reflective film 13 is arranged to be largerthan the area of the first light-transmissive member 3, preferably aplate-shape is employed fro the first light-reflective film 13.

Further, when the first light-reflective film is formed in advance andbonded with an adhesive, an adhesive such as acrylic, urethane, stylene,epoxy, polyimide, silicone, BT-resin, esther, ether, uria, polyamid,phenol, celluose derivative adhesive can be used alone or incombination.

Further, when a dielectric multi-layer film is used, a DBR-film(distributed Brag reflector) can be used. For the first light-reflectivefilm 13, above all, a film containing a dielectric multi-layer film ispreferably used. With a dielectric multi-layer film, the lightabsorption is less compared with a reflective film formed from a metal,and thus the light can be reflected efficiently. When both a metal filmand a dielectric multi-layer film are used, the dielectric multi-layerfilm and the metal film are arranged preferably in this order from thesurface to be placed. Further, when a metal film is used for the firstlight-reflective film 13, aluminum or silver alone or an alloy of themcan be used.

It should be noted that the other parts of the configuration of thelight-emitting device are similar to those which are explained abovealready.

Further, in the light-emitting device explained above for eachembodiment, the construction of the first light-transmissive member 3 ofthe package 10 may be such as shown in FIGS. 10A and 10B. FIGS. 10A and10B are schematical drawings each schematically showing a variant ineach embodiment. It should be noted that the members are shown forvisibility without hatching which indicates cross sections of themembers.

In the package 10A, the first light-transmissive member 3A is formed insuch a way that it covers the lateral surface and the second surface ofthe light-emitting element 1. This first light-transmissive member 3A ismade of a same material as explained already. Since the firstlight-transmissive member 3A is formed over the second surface, which isthe upper surface (lower surface in the figure) of the light-emittingelement 1, and over the lateral surface, it becomes easier to transferlight from the light-emitting element 1 to a distant part of thelight-guiding plate 30. Further, in the package 10B, it may be alsoacceptable that a second light-reflective film 14 is formed on the lowersurface of the first light-transmissive member 3A arranged on thelateral side and second surface of the light-emitting element 1 and onthe lower surface of the light-emitting element 1, so that the secondlight-reflective film 14 is formed to expose the element electrodes 5 ofthe light-emitting element 1. The second light-reflective film 14 may beformed employing a white resin for diffuse reflection or employing amaterial similar to that of the already explained second coveringmember. In the package 10B, the light extraction efficiency of thelight-emitting element 1, which light is emitted from the side of thelight-guiding plate 2, can be improved by providing the secondlight-reflective film 14.

It should be noted that, when any one of the packages 10A, 10B shown inFIGS. 10A, 10B is arranged on the light-guiding plate 30, the package isused in a state that the first light-reflective film 13 is arranged onthe upper surface of the first light-transmissive member 3A.

Next, a fifth embodiment is explained in reference to FIG. 11 . FIG. 11is a schematic crossectional view related to the fifth embodiment. Here,explanations are given, assuming a condition that, in the step ofpreparing an intermediate product, the package 10 is arranged on thelight-guiding plate 31 via the third light-transmissive member 40. Inthe figure, for better visibility, the hatchings showing the package andthe third light-transmissive member are omitted. In the light-emittingdevice related to the fifth embodiment, the difference from the secondembodiment shown in FIG. 6 is that a first auxiliary wiring 21 a 1 isformed on the first wiring 21 a and that a second auxiliary wiring 21 b1 is formed on the second wiring 21 b. Namely, in the fifth embodiment,a sag may be occasionally formed on the surface of the second coveringmember 50 when one or both resin materials of the reflective member 70and the second covering member 50 are cured and shrinked, wherein thereflective member 70 is filled in the second recess 31 b which is formedon the light-guiding plate 31. Therefore, for keeping flatness, thefirst auxiliary wiring 21 a 1 is arranged on the first wiring 21 a andthe second auxiliary wiring 21 b 1 is arranged on the first wiring 21 b.

Further, because a sag may be formed on the surface of the secondcovering member 50, there may be a risk that the first wiring 21 a andthe second wiring 21 b are formed narrower or thinner, causing a highelectrical resistance for these wirings. For avoiding this, the firstauxiliary wiring 21 a 1 is arranged on the first wiring 21 a and thesecond auxiliary wiring 21 b 1 is arranged on the first wiring 21 b,which may provide a lower electrical resistance and prevent wiringdisconnection.

Here, the employed first auxiliary wiring 21 a 1 is formed on the firstwiring 21 a by arranging a material of same width and same thickness asthe first wiring 21 a, which compensates the sag of the resin materialsto be close to a flat shape. Further, also the second auxiliary wiring21 b 1 is formed over the second wiring 21 b by arranging a material ofsame width and same thickness as the first wiring 21 b, compensating therecess to be close to a flat shape. It should be noted that the firstauxiliary wiring 21 a 1 and the second auxiliary wiring 21 b 1 may beformed from more than 1 layer, for keeping the flatness.

Further, the first auxiliary wiring 21 a 1 and the second auxiliarywiring 21 b 1 may be formed with a width larger than those of the firstwiring 21 a and the second wiring 21 b. In addition, the first auxiliarywiring 21 a 1 is formed having a length more than 50% of the length ofthe first wiring 21 a and is formed so far that the recessed portion canbe compensated to be flat. The second auxiliary wiring 21 b 1 issimilarly formed having a length more than 50% of the length of thesecond wiring 21 b. It should be noted that the first auxiliary wiring21 a 1 and the second auxiliary wiring 21 b 1 may be formed having asame length or may be formed having different lengths.

The first auxiliary wiring 21 a 1 and the second auxiliary wiring 21 b 1may be formed by printing, etc., similarly to the first wiring 21 a andsecond wiring 21 b. The first auxiliary wiring 21 a 1 and the secondauxiliary wiring 21 b 1 are preferably arranged on the first wiring 21 aand on the second wiring 21 b, extending over the portions having alargest recess and over a connecting portion of adjacent cells.

Next, a sixth embodiment is explained in reference to FIG. 12 . FIG. 12is a schematic crossectional view related to the sixth embodiment. Here,in the step of preparing an intermediate product, explanations are givenassuming a condition that the package 10 is arranged on thelight-guiding plate 31 via the third light-transmissive member 40. Inthe figure, for better visibility, the hatchings showing the package andthe third light-transmissive member are omitted. In the light-emittingdevice 100D related to the sixth embodiment, the difference from thesecond embodiment shown in FIG. 6 is that the second covering member 50is formed in the second recess 31 b of the light-guiding plate 31 andthat the third light-reflective film 15 is formed on the surfaceopposite to the light-emitting side of the light-guiding plate 31, alongthe shape of the second recess 31 b formed in the light-guiding plate31.

The third light-reflective film 15 is arranged to cover a surface of oneside of the light-guiding plate 31, excluding the first recess 31 a. Thethird light-reflective film 15 is preferably formed with a materialwhich shades or reflects at least 80% of light, for example. For thethird light-reflective film 15, a single-layer film from a metal, amulti-layer film from a metal, or a multi-layer film consisting of aplurality of layers from at least 2 two kinds of dielectric materials,namely a dielectric multi-layer film, can be used. Further, the thirdlight-reflective film can be formed, for example, by sputtering method.For this third light-reflective film 15, a material and a forming methodwhich are similar to the already explained first light-reflective filmcan be employed.

In addition, the light-emitting device 100D is formed in such a way thatthe second covering member 50 is filled in the second recess 31 b of thelight-guiding plate 31. In the light-emitting device 100D, theelectrodes 5 of the light-emitting element 1 may be electricallyconnected via a connection substrate 90.

The connection substrate 90 includes a wiring layer 91 in the substrateand includes a covering layer 92 formed from an insulating material forprotection of the wiring layer 91. The wiring substrate 90 includes thewiring layer 91 arranged on the surface of or within a flat plate-likesupporting member. It should be noted that, in the structure of thewiring substrate 90, number of light-emitting elements 1 andconstruction of the element electrodes such as shape and size of theelectrodes are determined according to the size of the light-emittingdevice.

For the supporting member of the wiring substrate 90, an insulatingmaterial is preferably used, and a material, which hardly transmits theemitted light from the light emitting element 1 or the external light,is preferably used. The wiring substrate 90 may be of a material havinga certain rigidity or may be of a material used for a sheet and aflexible substrate. In particular, a ceramic such as alumina, aluminiumnitride, mullite, and a resin such as phenol resin, epoxy resin,polyimide resin, BT resin (bismaleimide-triazin resin), polyphthalamide(PPA) can be considered.

The wiring 91 includes a first wiring 91 a electrically connected to thefirst electrode 5 a of the package 10 and a second wiring 91 belectrically connected to the first electrode 5 b of the package 10.Though the positions of the formed first wiring 91 a and second wiring91 b are different, their material, etc. are unchanged from the alreadyexplained wirings. Further, the wiring layer 91 is covered by a coveringlayer 92, excluding the positions of the electrodes 5.

The covering layer 92 is for protection of the wiring layer 91. Thecovering layer 92 is formed from an insulating material containing, forexample, polyimide as a base material. The covering layer 92 is formedby screen printing etc. using a mask in such a way as to cover thewiring layer 91 and to provide an opening 92 a on the position of theelectrode 5.

It should be noted that the wiring layer 91 of the wiring substrate 90is formed before electrical connections of the first and secondelectrodes 5 a, 5 b of the package 10, namely formed in the step offorming paired wirings for avoiding short circuiting of the connections.

Because the light-emitting device 100D includes the above explainedconstruction, owing to the third light-reflective film 15, thelight-emitting device can be used without deterioration of irradiationefficiency of light from the light-guiding plate 31.

Next, a seventh embodiment is explained in reference to FIG. 13 . FIG.13 is a schematic crossectional view related to the seventh embodiment.It should be noted that, for the already explained constructionelements, same numbers are given to them and their explanations areomitted. Further, here, in the step of preparing an intermediateproduct, explanations are given assuming a condition that the package 10is arranged on the light-guiding plate 31 via the thirdlight-transmissive member 40. Further, it is assumed that the firstwiring 21 a and the second wiring 21 b are formed in the step of formingpaired wirings in such a way that a wiring portion formed from a metalpaste layer is irradiated with a laser light to remove the metal pastelayer partially. In the light-emitting device 100E related to theseventh embodiment, the difference is in that the two layers of theinsulating member 60 are provided to flatten a recess occurring in thesecond covering member 50.

Namely, in the light-emitting device 100E, the flatness can be assuredby covering the recess portion in the second covering member 50 by useof two layers, a insulating layer 60 a and an auxiliary insulating layer60 b. Owing to this construction, in the light-emitting device 100E, itcan be facilitated to compensate the precision of applications ofrespective member and to improve the working efficiency per hour. Theauxiliary insulating film 60 b is not limited to one layer and may bemore than one layer. Further, it is sufficient if the insulating film 60a covers at least a part of the second covering member 50 and the pairof wirings 21. For example, the insulating film 60 a is formed in thecondition that the portions of electrical connections of the pairedwirings 21 is opened.

It should be noted that, in the first through seventh embodiments, byvirtue of the drawings, the figures indicating the structure parts inwhich the second covering member 50 is formed and the figures indicatingthe structure parts in which the second covering member 50 and thereflective member 70 are formed are mixedly shown. However, it isneedless to say that the respective embodiments can take anyconstruction, a construction in which the second covering member 50 isformed on the light guiding plate 30, 31, a construction in which thesecond covering member 50 and the reflective member 70 are included inthe light-guiding plate 30, 31, and so on.

Further, in the respective embodiments, it is acceptable that thelight-emitting device is constructed including the widened portions 21c, 22 c and including the insulating film 60 a and/or the auxiliaryinsulating film 60 b.

Although the present disclosure has been described with reference toseveral exemplary embodiments, it shall be understood that the wordsthat have been used are words of description and illustration, ratherthan words of limitation. Changes may be made within the purview of theappended claims, as presently stated and as amended, without departingfrom the scope and spirit of the disclosure in its aspects. Although thedisclosure has been described with reference to particular examples,means, and embodiments, the disclosure may be not intended to be limitedto the particulars disclosed; rather the disclosure extends to allfunctionally equivalent structures, methods, and uses such as are withinthe scope of the appended claims.

One or more examples or embodiments of the disclosure may be referred toherein, individually and/or collectively, by the term “disclosure”merely for convenience and without intending to voluntarily limit thescope of this application to any particular disclosure or inventiveconcept. Moreover, although specific examples and embodiments have beenillustrated and described herein, it should be appreciated that anysubsequent arrangement designed to achieve the same or similar purposemay be substituted for the specific examples or embodiments shown. Thisdisclosure may be intended to cover any and all subsequent adaptationsor variations of various examples and embodiments. Combinations of theabove examples and embodiments, and other examples and embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

In addition, in the foregoing Detailed Description, various features maybe grouped together or described in a single embodiment for the purposeof streamlining the disclosure. This disclosure may be not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive subject matter may bedirected to less than all of the features of any of the disclosedembodiments. Thus, the following claims are incorporated into theDetailed Description, with each claim standing on its own as definingseparately claimed subject matter.

The above disclosed subject matter shall be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments which fall within thetrue spirit and scope of the present disclosure. Thus, to the maximumextent allowed by law, the scope of the present disclosure may bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents and shall not be restricted or limited bythe foregoing detailed description.

The invention claimed is:
 1. A light-emitting device comprising: apackage comprising: a light-emitting element comprising a first surfaceand a second surface opposite to the first surface; a firstlight-transmissive member arranged on the second surface of thelight-emitting element; paired electrodes at the first surface of thelight-emitting element; and a first covering member covering thelight-emitting element such that the paired electrodes are exposed fromthe first covering member; a light-guiding plate on which the package isplaced; a second covering member arranged on the light-guiding plate andcovering laterally the package; paired wirings continuously covering thepaired electrodes exposed and the first covering member and beingconnected to the paired electrodes respectively, the paired wiringscomprising a mixture of a resin and metal powder; and a secondlight-transmissive member arranged in lateral sides of thelight-emitting element, wherein a part of the first covering layerarranged between the paired electrodes is removed.
 2. The light-emittingdevice according to claim 1, wherein the second light-transmissivemember is arranged between the second surface of the light-emittingelement and the first light-transmissive member, and wherein the secondlight-transmissive member bonds the second surface of the light-emittingelement to the first light-transmissive member.
 3. The light-emittingdevice according to claim 1, wherein the light-emitting element isplaced on the first light-transmissive member, and wherein the secondlight-transmissive member has an outer surface which extends obliquelyupward to the package.
 4. The light-emitting device according to claim1, wherein at least one groove between the paired electrodes has a widthof 10 μm to 100 μm and a depth of 0.1 μm to 3 μm.
 5. The light-emittingdevice according to claim 1, wherein the paired electrodes havethicknesses of 1 μm to 50 μm.
 6. The light-emitting device according toclaim 1, wherein the metal powder has a particle size of 0.01 μm to 10μm.
 7. The light-emitting device according to claim 1, wherein the metalpowder contained in the paired wirings has a concentration of 60 wt % to95 wt % to each wire.
 8. The light-emitting device according to claim 1,wherein the first covering member has a groove.
 9. The light-emittingdevice according to claim 1, wherein the light-guiding plate has a firstrecess or a through-hole, wherein the package or the light-emittingelement is arranged in the first recess or the through-hole, and whereina third light-transmissive member bonding the package or thelight-emitting element to the light-guiding plate is arranged in thefirst recess or the through-hole.
 10. The light-emitting deviceaccording to claim 9, wherein the first recess has a depth equal to orsmaller than a height of the package.
 11. The light-emitting deviceaccording to claim 9, wherein the third light-transmissive member has anouter surface extending obliquely upward to the package.
 12. Thelight-emitting device according to claim 9, wherein the light-guidingplate further has a third recess opposite to the first recess, wherein alight-blocking member is arranged in the third recess.
 13. Thelight-emitting device according to claim 9, wherein the light-guidingplate further has a second recess, wherein the second recess has alattice pattern between the neighboring first recesses and around anintersection point of a longitudinal line and a lateral line.
 14. Thelight-emitting device according to claim 13, wherein the paired wiringseach include a widened portion wider than a remaining portion of eachwiring, wherein the widened portion is arranged in the second recess.15. The light-emitting device according to claim 1, wherein the pairedelectrodes are covered with an insulating member.
 16. The light-emittingdevice according to claim 15, wherein the insulating member is colored.17. The light-emitting device according to claim 15, wherein theinsulating member is transparent or translucent.
 18. The light-emittingdevice according to claim 15, wherein the insulating member has a lighttransmission of 20% to 95%.
 19. The light-emitting device according toclaim 15, wherein the insulating member has a thickness of 0.5 μm to 100μm.
 20. A light-emitting device comprising: a package comprising: alight-emitting element comprising a first surface and a second surfaceopposite to the first surface; a first light-transmissive memberarranged on the second surface of the light-emitting element; pairedelectrodes at the first surface of the light-emitting element; and afirst covering member covering the light-emitting element such that thepaired electrodes are exposed from the first covering member; alight-guiding plate on which the package is placed; a second coveringmember arranged on the light-guiding plate and covering laterally thepackage; paired wirings continuously covering the paired electrodesexposed and the first covering member and being connected to the pairedelectrodes respectively, the paired wirings comprising a mixture of aresin and metal powder; and a third light-transmissive member bondingthe package or the light-emitting element to the light-guiding plate,wherein a part of the first covering layer arranged between the pairedelectrodes is removed, wherein the light-guiding plate has a firstrecess or a through-hole, wherein the package or the light-emittingelement is arranged in the first recess or the through-hole, and whereina third light-transmissive member is arranged in the first recess or thethrough-hole.
 21. A light-emitting device comprising: a packagecomprising: a light-emitting element comprising a first surface and asecond surface opposite to the first surface; a first light-transmissivemember arranged on the second surface of the light-emitting element;paired electrodes at the first surface of the light-emitting element;and a first covering member covering the light-emitting element suchthat the paired electrodes are exposed from the first covering member; alight-guiding plate on which the package is placed; a second coveringmember arranged on the light-guiding plate and covering laterally thepackage; and paired wirings continuously covering the paired electrodesexposed and the first covering member and being connected to the pairedelectrodes respectively, the paired wirings comprising a mixture of aresin and metal powder, wherein a part of the first covering layerarranged between the paired electrodes is removed, and wherein at leastone groove between the paired electrodes has a width of 10 μm to 100 μmand a depth of 0.1 μm to 3 μm.